Delay line for traveling wave tubes, especially for millimeter-waves, constructed from a plurality of laddershaped structures, bent to form a spiral line



w. VEITH ETAL 3,287,668

ESPECIALLY FOR CONSTRUCTED FROM A PLURALITY Nov. 22, 1966 DELAY LINE FORTRAVELING WAVE TUBES,

MILLIMETER-WAVES,

OF LADDERSHAPED STRUCTURES,BENT TO FORM A SPIRAL LINE 2 Sheets-Sheet 1Filed Oct. 13, 1964 Fig.2

ETAL DELAY LINE FOR TRAVELING WAVE TUBES, ESPECIALLY FOR MILLIMETER-VES, CONSTRUCTED FROM A PLURALITY OF DDERSHAPED STRUCTURES,BENT

TO FORM A SPIRAL LINE Nov. 22, 1966 w m 3,287,668

Filed Oct. 15, 1964 2 Sheets-Sheet 2 Fig.4

INVEpTC Z IZS Werner e/ A on/"ac/ 0b/ ATTYS.

United States Patent Claims. 61. 333-41 The invention relates to a delay:line for moving field tubes, especially for the amplification ofmillimeter waves, which consists of a spiral arranged in the interior ofan electrically conductive hollow body and in which the individualwindings are rigidly mounted on metal supports, which extend inwardlyfrom the wall of the hollow body toward the spiral and are progressivelyolfset against one another in the longitudinal direction of the spiral.In such a line it has already been proposed that the spiral be composedof arcuate-shaped sections which are disposed in planes perpendicular tothe iongitudinal axis of the delay line between two adjacent metalsupports, and straight sections which extend in the longitudinaldirection of the delay line.

According to the present invention it is proposed, in a delay line ofthe type described, that the spiral and the metal supports be producedfrom several stamped sheet metal strips which, as a development of thearcuate-shaped sections of the spiral and of the contiguous metalsupports, have the form of a ladder whose rungs are stepped, formingalternately towards the stringers of the ladder-shaped structure a halfsupport member, and are so assembled, in star form, continuously in thecircumferential direction of the spiral that the central portion of therungs form the arcuate-shaped sections of the spiral, while thelongitudinally extending sections of the delay line are formed by theside portions of the step-like offsets of the rungs extending parallelto the stringers.

A delay line proposed aclciording to the invention has, in the firstplace, the advantage that there results an extremely low capacitanceloading of the delay line from winding to winding of the spiral. Thiscorresponds to a high line impedance and, therefore, to a high couplingresistance of the delay line. On the other hand, a delay line accordingto the invention is simple from the viewpoint of manufacturingtechnology and can be produced very accurately as to its dimensions, inview of which it is especially suitable as 'a delay line for millimeterwave operation which, as is well known, requires very small geometricdimensions. In the production of such a delay line the sheet metalstrips are simply bent about a mandrel assembled thereon and solderedtogether, prior to their insertion in the hollow conductor.

In the drawings, wherein like reference numerals indicate like orcorresponding parts:

FIG. 1 is a perspective view of a portion of a spiral line embodying theinvention, with portions broken away to show the details thereof;

FIG. 2 is a development of one of the strips forming the structureillustrated in FIG. 1;

FIG. 3 is an end view of a hollow body in which the spiral line assemblyof FIG. 1 is to be received;

FIG. 4 schematically illustrates the spiral current path of thestructure illustrated in FIG. 1; and

FIG. 5 is a transverse sectional view through a delay line embodying theinvention, utilizing a hollow con- 'ductor formed from a plurality oflongitudinally extending members of arcuate cross-section.

The spiral line illustrated in FIG. 1, with the supports therefor, iscomposed of six stamped sheet metal strips 1, individually illustratedin FIG. 2. Such sheet metal strips 1 are suitably formed, as by stampingin the shape of a ladder, whose rungs, indicated generally by thereference numeral 2, are alternately stepped toward the stringers 3. Asis apparent from FIGS. 1 and 2, the central portion of rungs 2 having auniform width or height as viewed in FIG. 2, represents the developmentof the arcuate-formed sections 4 of the spiral, which are disposed inplanes perpendicular to the longitudinal axis of the delay line. Thestepwise enlarged ends of the rungs 2 form in each case a half supportmember 5. The portions 5 extending parallel to the stringer-s 3, of thestep-like offsets of rungs 2, define sections of the spiral line whichextend in longitudinal direction of the delay line.

FIG. 4 schematically illustrates the spiral current path through thedelay line.

In a delay line according to the invention, the spiral with metalsupports as illustrated in FIG. 1 is to be so arranged on anelectrically conductive hollow body that the metal supports 5 supportthe spiral line within the hollow body. As illustrated in FIG. 3, forthis purpose there are provided in the hollow cylindrical metal body 6longitudinally extending grooves 7 whose depth b corresponds to thewidth of the stringers 3 and whose width a corresponds to twice thestringer thickness. The sheet metal strips of FIG. 2 following arcuateformations of the rungs '2, and assembly according to FIG. 1, can thenbe inserted in the hollow body 6 in such a way that the stringers 3 ofthe sheet metal strips are disposed within the wall of the hollow body6, the stringers 3 expediently being soldered in the 1onlgitudinalgrooves 7 thereof.

In the embodiment of the invention illustrated, the angle which twometal supports of a strip enclose with respect to one another amounts to60. The invention is obviously not limited to such a supporting angle.On the contrary, the metal supports may enclose any angle with respectto one another, which in the assembled structure total 360.

In a delay line according to the invention, as illustrated in FIG. 5,the hollow conductor may also be composed of several parts. Such a delayline can be manufactured in a particularly simple manner if, in thearrangement shown in FIG. 1, longitudinally extending strips 8, ofarcuate cross section, as assembled between the respective spaced pairsof stringers 3 disposed in a star pattern, which upon soldering of theassembly produces a hollow body, having a cross-section as illustratedin FIG. 5.

Changes may be made within the scope and spirit of the appended claimswhich define what is believed to be new and desired to have protected byLetters Patent.

We claim:

1. A delay line for moving field tubes, especially for the amplificationof millimeter waves, which consist of a spiral arranged in the interiorof an electrically conductive hollow body, with individual windingsrigidly attached to met-a1 supports which extend inwardly from the Wallof the hollow body toward the spiral and are angularly offset withrespect to one another progressively in the hollow body in thelongitudinal direction of the spiral, the spiral comprisingarcuate-shaped sections which are disposed between two adjacent metalsupports in respective planes extending perpendicular to thelongitudinal axis of the delay line, and straight sections which extendin the longitudinal direction of the delay line, characterized in thatthe spiral and the metal supports are made of a plurality of stampedsheet metal strips which, as a development of the arcuate-shapedsections and of the adjoining metal supports, have the form of a ladderwhose rungs are stepped alternately toward the stringers thereof formingin each case a. half support member, the formed strips beinginterassembled progressively in a star pattern in circumferentialdirection of the spiral whereby the central portion of the rungs formthe arouate-shaped sections of the spiral, while the longitudinallyextending sections of the delay line are formed by the step-likeportions of the rungs extending parallel to the stringers. I

2. A delay line according to claim 1, wherein the stningers of theladder-shaped sheet metal strips are disposed within the wall of thehollow body.

3. A delay line according to claim 2, wherein the hollow body has acircular cross-section.

4. A delay line according to claim 3, wherein there is provided in theinterior wall of the hollow body a plurality of longitudinal groovescorresponding to the number of metal supports distributed about thecircumference of the hollow body, the depth of such groovescorresponding to the width of the ladder stringers and the width of suchgrooves corresponding to twice the thickness of the ladder stringers,the ladder being dis posed in corresponding grooves and secured to thehollow body.

5. A delay line according to claim 3, wherein the hollow body isconstructed of longitudinally extending segments which are arrangedbetween separated pairs of stringers resulting from a star pattern ofthe laddershaped sheet metal strips, and secured thereto.

No references cited.

HERMAN KARL SAALBACH, Primary Examiner.

R. D. COHN, Assistant Examiner.

1. A DELAY LINE FOR MOVING FIELD TUBES, ESPECIALLY FOR THE AMPLIFICATIONOF MILLIMETER WAVES, WHICH CONSIST OF A SPIRAL ARRANGED IN THE INTERIOROF AN ELECTRICALLY CONDUCTIVE HOLLOW BODY, WITH INDIVIDUAL WINGINGSRIGIDLY ATTACHED TO METAL SUPPORTS WHICH EXTEND INWARDLY FROM THE WALLOF THE HOLLOW BODY TOWARD THE SPIRAL AND ARE ANGULARLY OFFSET WITHRESPECT TO ONE ANOTHER PROGRESSIVELY IN THE HOLLOW BODY IN THELONGITUDINAL DIRECTION OF THE SPIRAL, THE SPIRAL COMPRISINGARCUATE-SHAPED SECTIONS WHICH ARE DISPOSED BETWEEN TWO ADJACENT METALSUPPORTS IN RESPECTIVE PLANES EXTENDING PERPENDICULAR TO THELONGITUDINAL AXIS OF THE DELAY LINE, AND STRAIGHT SECTIONS WHICH EXTENDIN THE LONGITUDINAL DIRECTION OF THE DELAY LINE, CHARACTERIZED IN THATTHE SPIRAL AND THE METAL SUPPORTS ARE MADE OF A PLURALITY OF STAMPEDSHEET METAL STRIPS WHICH, AS A DEVELOPMENT OF THE ARCUATE-SHAPEDSECTIONS AND OF THE ADJOINING METAL SUPPORTS, HAVE THE FORM OF A LADDERWHOSE RUNGS ARE STEPPED ALTERNATELY TOWARD THE STRINGERS THEREOF FORMINGIN EACH CASE A HALF SUPPORT MEMBER, THE FORMED STRIPS BEINGINTERASSEMBLED PROGRESSIVELY IN A STAR PATTERN IN CIRCUMFERENTIALDIRECTOIN OF THE SPIRAL WHEREBY THE CENTRAL PORTION OF THE RUNGS FROMTHE ARCUATE-SHAPED SECTIONS OF THE SPIRAL, WHILE THE LONGITUDINALLYEXTENDING SECTIONS OF THE DELAY LINE ARE FORMED BY THE STEP-LIKEPORTIONS OF THE RUNGS EXTENDING PARALLEL TO THE STINGERS.